This application is directed to a video signal compression system, and more particularly to the compression of video information signals to permit recording of video information at high speed and on a smaller recording area.
Home video systems have recently become quite popular, with the user being provided with a video cassette player and a portable video camera which will record video information on a magnetic tape cassette to be later played back and displayed on a home television receiver.
A conventional image pick-up device may include 242 rows of 256 pixels each, or a total of 61,952 pixels for each frame of video information. If the display device displays 30 frames per second, the data to be recorded on the tape may be 1.8 million pixels per second. If the fields are not interlaced in the display processing, 60 frames per second may be required thus doubling the pixel data rate. If each pixel is represented by, e.g. 8 bits, one can see that the bit rate would be extremely high. This has led to the requirement of high speed recording circuitry and large capacity recording tapes. For this reason, conventional VTR devices have been quite bulky and difficult to incorporate into a small hand-held camera. A typical arrangement would have the imaging system in the camera connected via a cable hook-up to a recorder carried by a shoulder strap.
Even if the recorder electronics are made as small as possible, conventional recording techniques still require a substantial storage area and therefore have used relatively large cassette tapes. Even assuming that the recorder electronics could be incorporated into the camera body, a camera large enough to accommodate a typical video cassette tape would still be quite cumbersome.
It would be desirable, therefore, to provide a video signal processing system which is capable of recording the video image data in a much smaller recording area without sacrificing image integrity, thereby enabling the use of a very small cassette tape, e.g. similar in size to a conventional audio cassette tape. This would permit the camera and recording circuitry to be incorporated into a single easily portable camera body, and would significantly enhance the versatility of such a system.
Further, even if a signal processing system is designed which will enable recording of the data on a smaller recording area, it is also a problem that conventional audio cassette tapes have difficulty handling high data recording speeds, and it would therefore be desirable to provide a video signal processing system which would enable the recording of the video data at a much reduced rate. This would enable the use of conventional audio cassette tapes which are readily available and inexpensive.